<template>
    <div class="s-canvas">
        <canvas id="s-canvas" :width="contentWidth" :height="contentHeight"></canvas>
    </div>
</template>
 
<script>
import { watch, onMounted } from 'vue'
export default {
    name: "SIdentify",
    props: {
        identifyCode: {
            type: String,
            default: '1234'
        }, fontSizeMin: {
            type: Number,
            default: 30
        },
        fontSizeMax: {
            type: Number,
            default: 35
        },
        backgroundColorMin: {
            type: Number,
            default: 255
        },
        backgroundColorMax: {
            type: Number,
            default: 255
        },
        colorMin: {
            type: Number,
            default: 0
        },
        colorMax: {
            type: Number,
            default: 160
        },
        lineColorMin: {
            type: Number,
            default: 100
        }, lineColorMax: {
            type: Number,
            default: 255
        },
        dotColorMin: {
            type: Number,
            default: 0
        },
        dotColorMax: {
            type: Number,
            default: 255
        },
        contentWidth: {
            type: Number,
            default: 120
        },
        contentHeight: {
            type: Number,
            default: 30
        }
    },
    setup(props) {
        watch(() => props.identifyCode, () => {
            drawPic()
        })
        // 生成一个随机数
        const randomNum = (min, max) => {
            return Math.floor(Math.random() * (max - min) + min)
        }

        // 生成一个随机的颜色
        const randomColor = (min, max) => {
            let r = randomNum(min, max)
            let g = randomNum(min, max)
            let b = randomNum(min, max)
            return 'rgb(' + r + ',' + g + ',' + b + ')'
        }

        const drawPic = () => {
            let canvas = document.getElementById('s-canvas')
            let ctx = canvas.getContext('2d')
            ctx.textBaseline = 'bottom'
            // 绘制背景
            ctx.fillStyle = randomColor(props.backgroundColorMin, props.backgroundColorMax)
            ctx.fillRect(0, 0, props.contentWidth, props.contentHeight)
            // 绘制文字
            for (let i = 0; i < props.identifyCode.length; i++) {
                drawText(ctx, props.identifyCode[i], i)
            }
            drawLine(ctx)
            drawDot(ctx)
        }

        const drawText = (ctx, txt, i) => {
            ctx.fillStyle = randomColor(props.colorMin, props.colorMax)
            ctx.font = randomNum(props.fontSizeMin, props.fontSizeMax) + 'px SimHei'
            let x = (i + 1) * (props.contentWidth / (props.identifyCode.length + 1))
            let y = randomNum(props.fontSizeMax, props.contentHeight - 5)
            var deg = randomNum(-45, 45)
            // 修改坐标原点和旋转角度
            ctx.translate(x, y)
            ctx.rotate(deg * Math.PI / 180)
            ctx.fillText(txt, 0, 0)
            // 恢复坐标原点和旋转角度
            ctx.rotate(-deg * Math.PI / 180)
            ctx.translate(-x, -y)
        }
        const drawLine = (ctx) => {
            // 绘制干扰线
            for (let i = 0; i < 3; i++) {
                ctx.strokeStyle = randomColor(props.lineColorMin, props.lineColorMax)
                ctx.beginPath()
                ctx.moveTo(randomNum(0, props.contentWidth), randomNum(0, props.contentHeight))
                ctx.lineTo(randomNum(0, props.contentWidth), randomNum(0, props.contentHeight))
                ctx.stroke()
            }
        }
        const drawDot = (ctx) => {
            // 绘制干扰点
            for (let i = 0; i < 30; i++) {
                ctx.fillStyle = randomColor(0, 255)
                ctx.beginPath()
                ctx.arc(randomNum(0, props.contentWidth), randomNum(0, props.contentHeight), 1, 0, 2 * Math.PI)
                ctx.fill()
            }
        }
        onMounted(() => {
            drawPic()
        })

        return {
            // 状态

            // 事件
        }
    }
}
</script>
 
<style scoped>
.s-canvas {
    height: 38px;

}

.s-canvas canvas {
    margin-top: 1px;
    margin-left: 8px;
}
</style>